Dentistry



UNITED STATES PATENT OFFICE.

CHARLES MOLEAN, OF BOSTON, MASSACHUSETTS.

DENTISTRY.

SPECIFICATION forming part of Letters Patent No. 363,904, dated May 31, 1887.

Application filed December 27, 1886. Serial No. 222,662. (Specimens) To all whom it may concern:

Be it known that 1, CHARLES MOLEAN, of

Boston, in the county of Suffolk and State of Massachusetts, a citizen of the United States, have invented a new and useful Improvement in the Art of Dentistry, of which the following is a full, clear, and exact description.

In the manufacture of dentures of vulcanized india-rubber the mold in which they are vulcanized is usually formed of plaster, that being the most convenient material for obtaining the counterpart of the wax model which is obtained directly from the month. In vulcanizing in plaster molds it frequently hap- I 5 pens that the rubber and plaster so adhere to each other that portions of the plaster are torn from the mold in the act of separation and adhere to the vulcanized plate with great tenacity. Hitherto it has been exceedingly (lifticult to separate the plaster from the plate without injuring either the plate or the teeth.

My invention consists of a process by which plaster is readily and quickly disintegrated and may be removed with great rapidity.

I take the plate Wit-h adhering plaster, and, the fingers of the operator being protected from casual spattering by an india rubber glove orfinger-cots, I brush upon the plaster with asmall brush a solution of hydrofluoric acid,which can now be obtained commercially, the principal use of which hitherto has been in the etching of glass. I have discovered that the commercial solution has very slight effect upon the enamel of artificial teeth, the 5 fact being that a contact of several hours hardly does more than to affect the surface polish. I use for this purpose a small common bristle'or camels-hair brush. The hydrofluoric acid immediately disintegrates the plaster, as if by a process of wet calcination, and 0 the dental plate being taken to a sink and scrubbed with 'an ordinary tooth-brush and washed, preferably with running water, the. plaster is immediately removed, much as if it weresimply adherent dust or mud, and the pol- 5 ish and color of the vulcanized plate are not interfered with. Something which will do this has long been a desideratum with dentists.

It is obvious that for any purpose where the disintegration of plaster is desirable substan- 5o tiallythe same process can be employed.

I claim as my invention and desire to secure by Letters Patent of the United States 1. That improvement in the art of dentistry, which consists in the rapid disintegration and removal of the plaster which adheres to vulcanized dental plates after vulcanization by disintegration caused by theapplication of an aqueous solution of hydrofluoric acid and subsequent washing and scrubbing in' water, substantially as described.

2. The process of removing adherent plaster-of-paris from objects to which it adheres, by means of an application of hydrofluoric acid to the plaster, substantially as described.

CHARLES MGLEAN.

IVitnesses:

THOS. WM. CLARKE, FIRED. B. DOLAN. 

